Lesson 6 - Radiation and Combined
This lesson deals with the principles and application of a form of heat transfer called radiation. This lesson will also combine the heat transfer methods you learned previously to provide an overall picture of heat transfer processes in a brewery.
Radiation Applications
Radiation occurs everywhere that heat is being transferred. However, the quantity of radiation heat can vary from negligible to very large contributions to overall heat transfer. Let’s look at some examples of radiation when the resulting heat transfer is substantial.
Solar energy is a great example of radiation heat transfer. A passive solar heater uses captured energy to heat indoor living areas.
Another example you would find in a brewery is a boiler, which actually uses all modes of heat transfer. A boiler burns fuel, an exothermic reaction which generates a high temperature and lots of heat. When fuel is combusted, most of the released energy is released via radiation by the products of combustion (CO2 and H2O).
An unlagged or uninsulated vessel in the brewhouse such as the hot water tank will have a substantial amount of heat loss via radiation. As the vessels in the brewhouse become tarnished and degraded, their emissivity increases and more heat energy is lost by radiation.
Vessels in the brewhouse lose heat by radiation.
When construction engineers design cooling for buildings, they account for the total heat gain possible through the exterior surfaces. The roof of a building and any external equipment are subject to solar radiation and heat gain.
Radiation is of increased importance for equipment placed outside, such as external bright beer tanks. When a building is designed, it is important to know how to control radiation so that tanks are placed in the best location and the correct construction materials are used.